Control modules for automatic transmissions in motor vehicles are installed in the transmission in such a way that they are entirely or partially immersed in transmission oil. These control modules contain an electronic system which must be packed in an oil-tight housing, so that aggressive transmission oil does not destroy the electronic system. This seal must be ensured within the operating temperature of the vehicle's automatic transmission, i.e., in a temperature range from approximately −40° C. to +150° C.
There are various approaches for packing the electronic system. For example, hermetically sealed steel housings with glass-sheathed pins may be used for electrical contacting of the electronic system. Housings manufactured by a so-called molding operation may also be used.
Such a molded housing, i.e., sealed using an encapsulating resin, is described in European Patent No. EP 1 396 885 B1. An interconnect device is fitted with electronic components and then completely enclosed in the molding compound, electrical contacting of the interconnect device to the outside being accomplished through a punched screen. The individual contact strips of the punched screen emerge from the molded housing at the side faces. In the control module, these contact strips are welded to the punched screen of the control module and are then covered by plastic covers which contain ribs that pass between the contact strips to thereby achieve short-circuit protection.
All contact strips must have adhesion to the molding compound on all side faces to ensure the oil tightness of the mold housing. This adhesion depends on many parameters, e.g., the geometry and distribution of the contact strips. With a change in the contact strip configuration, it may therefore be necessary to adjust the process accordingly.
Forces are also exerted on the contact strips due to welding of the punched screen of the control module, so these forces may also result in crack formation and therefore leakage of the mold housing. In addition to the forces introduced mechanically, the situation is also similar for forces introduced through thermal stresses, e.g., because of different expansion coefficients.
In manufacturing the mold housing, the two mold halves of the molding tool move toward the punched screen and form a seal with it. This means that the interspaces between the individual contact strips would also have to be sealed by the two mold halves, which, however, is technically complicated due to parts tolerances. Alternatively, the webs may also be punched out after the molding operation to obtain electrical separation of the individual contact strips. This necessitates an additional process step which also entails the risk of damage to the mold housing due to crack formation.
German Patent No. DE 103 15 432 A1 describes a configuration for electrically connecting an electrical unit which is situated in the interior of a metal housing and has flexible foil conductors leading out of the housing.